Disclosed is a method for preparing a metal catalyst composite. The method includes pre-treating a carbon support in a reactor, and depositing a metal precursor on the pre-treated carbon support. The pre-treating the carbon support may include exposing the carbon support to a nucleating agent, for example, titanium tetrachloride (TiCl4), silicon tetrachloride (SiCl4) and carbon tetrachloride (CCl4).